This Article Full Text Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Savage, D. B. Articles by O’Rahilly, S. Search for Related Content PubMed PubMed Citation Articles by Savage, D. B. Articles by O’Rahilly, S. Related Collections Lipid Metabolism

Energy Expenditure and Adaptive Responses to an Acute Hypercaloric Fat Load in Humans with Lipodystrophy

Departments of Clinical Biochemistry and Medicine, Addenbrooke’s Hospital, Cambridge CB2 2QQ, United Kingdom

Address all correspondence and requests for reprints to: Dr. Stephen O’Rahilly, Department of Clinical Biochemistry and Medicine, Level 4, Box 232, Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 2QQ, United Kingdom. E-mail: sorahill{at}hgmp.mrc.ac.uk.

Humans respond to an acute excess of ingested energy by storing the surplus energy as triglyceride in white adipose tissue. To study the energetic response to acute overfeeding in human subjects with limited adipose tissue capacity, we recruited seven subjects with lipodystrophy and seven lean healthy controls. Total fat mass was approximately 70% lower in lipodystrophic subjects (mean, 6.1 kg) than in body mass index-matched lean controls (mean, 22.0 kg). Energy expenditure and macronutrient oxidation rates were assessed in chamber calorimeters on two separate occasions for 40 h, during which time subjects consumed either an energy-balanced diet or a diet incorporating 30% excess energy as fat. On the energy-balanced diet, total daily energy expenditure and basal metabolic rate were linearly associated with lean mass in both groups (r² = 0.83) and were not significantly different between groups when corrected for lean mass. In response to the fat challenge, total energy expenditure did not increase significantly in healthy controls (9,472 ± 1,069 to 9,724 ± 1,114 kJ/d; P = 0.189). Substrate oxidation results confirm that excess fat was predominantly stored. In contrast, lipodystrophic subjects significantly increased total daily energy expenditure (11,081 ± 1,226 to 11,730 ± 1,374 kJ/d; P < 0.005). This was largely attributable to a 29% increase in fat oxidation. Thus, subjects with lipodystrophy uniquely respond to an acute hypercaloric load with a higher energy expenditure increment and by increasing fat oxidation. Insight into the molecular mechanisms responsible for this phenomenon may yield novel therapeutic approaches for obesity.

This article has been cited by other articles:

				L. A Kosmiski, B. M Ringham, G. K Grunwald, and D. H Bessesen Dual-energy X-ray absorptiometry modeling to explain the increased resting energy expenditure associated with the HIV lipoatrophy syndrome Am. J. Clinical Nutrition, December 1, 2009; 90(6): 1525 - 1531. [Abstract] [Full Text] [PDF]

				J. E. Galgani, C. Moro, and E. Ravussin Metabolic flexibility and insulin resistance Am J Physiol Endocrinol Metab, November 1, 2008; 295(5): E1009 - E1017. [Abstract] [Full Text] [PDF]

				L. A Kosmiski, D. H Bessesen, S. A Stotz, J. R Koeppe, and T. J Horton Short-term overfeeding increases resting energy expenditure in patients with HIV lipodystrophy Am. J. Clinical Nutrition, October 1, 2007; 86(4): 1009 - 1015. [Abstract] [Full Text] [PDF]

				D. B. Savage, K. F. Petersen, and G. I. Shulman Disordered Lipid Metabolism and the Pathogenesis of Insulin Resistance Physiol Rev, April 1, 2007; 87(2): 507 - 520. [Abstract] [Full Text] [PDF]

				K. C Hansen, Z. Zhang, T. Gomez, A. K Adams, and D. A Schoeller Exercise increases the proportion of fat utilization during short-term consumption of a high-fat diet Am. J. Clinical Nutrition, January 1, 2007; 85(1): 109 - 116. [Abstract] [Full Text] [PDF]